An ANZ spokesperson said the change reflected the localised downturn in Gladstone because it was dependent on the mining sector.

With the average house price in Gladstone sitting at $346,000, a home buyer would have to find $103,800.

Gladstone Home Loans mortgage broker Peter Miller said ANZ had shut the door on supplying home loans.

"I've had five customers in the last three weeks closing down their ANZ bank accounts," he said.

"But Gladstone is not a mining town. Thousands of people work in industry. Gladstone is self-reliant, it doesn't need mining.

"Mackay is more of a mining town and it's not on the list."

Ray White Gladstone principal Andrew Allen said Gladstone was no longer a risky market for banks.

"In theory this is the least risky time to lend money," he said.

"In 2011-12 the market peaked and the values have dropped considerably since then. That was when it was risky to lend money, not now."

Individual Home Loans mortgage broker John Whitten said ANZ was the only bank asking for a 30% deposit.

"A lot of banks want 5% and 10%," he said.

Out of the other four big banks, National Australia Bank does not have a blanket rule for deposits in Gladstone, Westpac does have areas with minimum deposit limits of 30% but Gladstone isn't included in that, and the Commonwealth Bank was "unable to assist" with our enquiry.